PYRIDO-OXAZOLYL-STILBENES, PROCEDE DE FABRICATION ET APPLICATION COMME PRODUIT A POLIR OPTIQUE

PYRIDO-OXAZOLYL-STILBENES, PROCESS FOR THEIR MANUFACTURE AND THEIR USE AS OPTICAL BRIGHTENERS

Abrégé anglais

Abstract
Compounds of the formula I
<IMG> I
in which X is 0 or S, R1 and R2, being identical or different, are radicals
selected from the group of hydrogen, fluorine or chlorine atoms, phenyl,
C1-C9-alkyl, C1-C4-alkoxy, C1-C4-dialkyl-amino, acylamino radicals, or optio-
nally functionally modified carboxy or sulfo groups, two adjacent radicals R1
and R2 together optionally representing a benzo ring, a lower alkylene or a
1,3-dioxapropylene group, and A is a group of the formulae
or <IMG>
<IMG>
in which R3 and R4, independently from each other, are hydrogen, fluorine or
chlorine atoms or C1-C4-alkyl groups; these compounds are useful as optical
brighteners.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Compounds of the formula Ia
<IMG> Ia
wherein R1 and R2 are the same or different and are selected from the group
consisting of hydrogen, chlorine, C1-C9-alkyl and phenyl and A is a group of
the formula
<IMG> or <IMG>
2. Compounds as claimed in claim 1, wherein R1 and R2, independently
from each other, are hydrogen or chlorine atoms in 5-, 6- or 7-position,
C1-C4-alkyl or phenyl.
3. A process for the manufacture of compounds as claimed in claim 1,
which comprises reacting a compound of the formula IIa
<IMG> IIa
or the functional acid derivative thereof with a compound of the formula IIIa
IIIa
<IMG>
16

wherein either Z is an amino group and Y a hydroxy group, or Y is an amino
group and Z a hydroxy group or a chlorine atom, and R1 and R2 are as defined
in claim 1.
4. The process as claimed in claim 3, which comprises reacting first a
compound of the formula IIa or the functional acid derivative thereof with a
compound of the formula IIIa to form the corresponding N-acyl compound, and
subsequently cyclizing this acyl compound by heating to form the product of
the formula Ia.
5. A process as claimed in claim 3 for the manufacture of compounds as
claimed in claim 1 wherein R1 and R2, independently from each other, are
hydrogen or chlorine atoms in 5-, 6- or 7-position, C1-C4-alkyl or phenyl.
17

Description

1~4~ 2
.
Subject of the present invention are compounds of the formula I
~3~</ i>-- CH = C}l ~ A
R X
in which X is 0 or S,
Rl and R2, being identical or different, are radicals selected from the group
. .
of hydrogen, fluorine or chlorine atoms, phenyl, Cl-Cg-alkyl, Cl-C4-alkoxy,
Cl-C4-dialkylamino, acylamino radicals, or optionally functionally modified
carboxy or sulfo groups, two adjacent radicals Rl and R2 together optionally
representing a benzo ring, a lower alkylene or a 1,3-dioxapropylene group,
and
- A is a group of the formulae
R
~4
in which R3 and R4, independently from each other, are hydrogen, fluorine or
chlorine atoms or Cl-C4 alkyl groups.
:
Especially interesting are those compounds of the formula I, in
which X, Rl and R2 are as defined above and R3 and R4, independently from
: each other, are hydrogen or methyl.
In particular, the present invention provides compounds of the
formula Ia.
R ~ < CH = CH _ A Ia
,~ ,~ ~ '

42
wherein Rl and R2 are the same or different and are selected from the group
consisting of hydrogen, chlorine, Cl-Cg-alkyl and phenyl and A is a group of
the formula
~ o~~ ~ or ~
Preferred compounds are above all those of the formula I, in which
X is 0, Rl and R2, independently from each other, are hydrogen or chlorine
atom in 5-, 6- or 7-position, Cl-C4-alkyl, phenyl or, together, are a fused
ben70 ring, and R3 and R4, independently from each other, are hydrogen.
By functionally modified carboxy groups, there are to be understood
generally carboxylic acid derivatives in every respect, that is, compounds
having one carbon atom which is linked to three hetero atoms, especially
oxygen, nitrogen and sulfur. In a more limited sense, there are to be under-
stood salts with colorless cations, alkali metal or ammonium ions being pre-
ferred, and furthermore a cyano, carboxylic acid ester or carboxylic acid
amide group. By carboxylic acid ester groups, there are to be understood
especially those of the formula COOQl, in which Ql is a phenyl radical or an
optionally branched lower alkyl group. By carboxylic acid amide group, there
is to be understood especially a group of the formula CoNQ2Q3, in which Q2
and Q3 are hydrogen atoms or optionally substituted lower alkyl groups which
may form a hydroaromatic ring together with the nitrogen atom.
By functionally modified sulfo groups, there are to be understood,
in analogy to the above details, radicals the sulfo group of which is linked
to a hetero atom, that is, salts with colorless cations, preferably alkali
metal or ammonium ions, and furthermore sulfonic acid ester groups and the
sulfonamide group. By sulfonic acid ester group, there is to be understood
~ ~ - 2 -

42
1 . .. 1 .
especlally a group of the formula S020Q , ln whIch Q lS as def m ed above,
and by sulfonamide group, there is to be understood a group of the formula
So2NQ2Q3, in which Q2 and Q3 are as defined above.
:
By acyl group, there is to be understood especially a group of the
formula CoQ4, in which Q4 is an optionally substituted, preferably lower,
alkyl radical, or a phenyl radical, especially the CoQ4 group is an unsub-
stituted Cl-C4-alkanoyl group or the benzoyl group.
- The novel compounds of the formula I can be prepared according to
different methods already known.
According to one of these manufacturing processes, compounds of the
;- formula II
~ C~l = CH ~3--COOH Il
,
are reacted, with or without intermediate isolation, and preferably in the
presence of catalysts, with compounds of the formula III
R
~ Y ~ 3
- 20 ~ N ~ III
in which either Z is an amino group and Y a hydroxy group or Y is an amino
group and Z a hydroxy group or a chlorine atom. Instead of the free acids of
the formula II, the functional derivatives thereof may alternatively be used
as starting materials, for example the corresponding alkyl ester or, prefer-
ably, the acid chloride. In the above formulae, the symbols X, Rl, R2, R3 and
R4 are as defined sub formula I.
In particular, the present invention provides a process for the
- 3 -

Z~2
manufacture of compounds as defined above, which comprises reacting a compound
of the formula II-a
~ ~ - Cll = C} _ C00~ lla
or the functional acid derivative thereof with a compound of the formula IIIa
) ~ Illa
wherein either Z is an amino group and Y a hydroxy group, or Y is an amino
group and Z a hydroxy group of a chlorine atom, and Rl and R2 are as defined
above.
The reaction of the components may be carried out with or without
intermediate isolation, by heating to elevated temperatures, for example to
120 to 330C, advantageously in an inert gas, for example a nitrogen current,
and the reaction is optionally carried out in the presence of a catalyst.
Suitable catalysts are for example boric acid, zinc chloride, ptoluenesulfonic
acid, furthermore polyphosphoric acids including pyrophosphoric acid. When
using boric acid as catalyst, it is employed advantageously in an amount of
from about 0.5 to
''^
~.~ 4
. ~ ,,

~ 2'~ iiOE 77/F 061
5 %, relati~e to the total weight of the reaction mass. ~7ig'n--
boi]ing, polar, organic solvents such as dimetr,y] formamide,
N-methylpyrrolidone, and aliphatic, optionally etherified, oxy
compounds, for example dialkyl carbinols, propvlene giycol~
ethyleneglycol-monoethyl ether or diethyleneglycol-diethyl
ether, and high-boiling esters Or phthalic acid, for example
phthalic acid dibutyl ester, may be used in addition.
Alternatively, this reaction may be carried out in two
steps by condensing the carboxylic acid of the foYmula II or
a functional derivati~Je thereof, especiaily a carboxylic acid
chloride, with a compound of the formula III in the presence
of an organic solvent such as toluene, xylylene, chlorobenzene,
dichlorobenzene, tetraline, trichlorobenzene or nitrobenzene,
at elevated temperatures, and converting the N-acyl compounds
so obtained to the compounds of formula I at elevated tempera-
tures and optionally in the presence of a catalyst. ~his opera-
tion mode is required especially in the case where Z in the
formula III is a chlorine atom. In this case, cyclization
:
- of the acyl compound obtained in the first step to a compound
- 20 of formula I has to be carried out according to known processes,
as described for example in British Patent No. 1,242,836 or
U.S. Patent No. 3,873,531, in the presence of copper acetate
and metallic zinc.
When carboxylic acid chlorides are used as starting sub-
stances of the formula II, they may be prepared i~mediately
prior to condensation with the compounds of formula III and
without intermediate isolation with thionyl chloride from
the free carboxylic acid in the same solvent in which subse-
29 quently the condensation with the compound III procerds.
-- 5 --

~ HOE 77/F 061
When Z i.n the formula III is an amino group and ~ a hy-
droxy group, compounds of the formula I are obtained having
an oxazolo-(4,5-b)-pyridine ring, while in the inverse case
compounds OI the formula I having an oxazolo-(5,4--b)-pyridine
ring are the result.
The free acids of the formula II and the corresponding
acid chlorides are known from the literat~re and can be ob-
tained according to processes descrlbed in the literature
~Japanese Patents Nos. 40,581/65, 44-6979, 7045/68, German
Offenlegungsschriften Nos. 2,306,050, 1,594,829, 2,129,816).
. They are obtained for example by the following reaction steps
known to those skilled i.n the art:
H3COOC- ~ -CU~CH- ~ -COOCH3
HOOC- ~ -CH-CH- ~ -COOCH3
CloC-~3-CH l-CH-~ -COOCH3
~ ~ 2
.. : R2 XH
~ ~ ~ -CH = CH- ~ -COOCH3
R2 ,
CH CH- ~ -COOH
CH = CH- ~ -COCl
R2
-- 6 --

HOE 77/F 061
The com~ounds of the formula III are known from the ii-
terature and can be obtained according to processes described
in the literature (German Offenlegungsschrift ~1o. 2,628,266,
French Patents Nos. 1,477,998, 1,522,261, British Patent No.
1,108,975, J.Chem.Soc.B 1971 !7) 1425-32).
The novel compounds of the formula I are nearly color
less to yellow fluorescing substances which are suitable as
optical brighteners and above all as blending component in
admixture with other optical brighteners.
The substrates to be brightened are for example the fol
lowing materials: lacquers, natural or synthetic fibers, for
example those of natural or regenerated cellulose, acetyl
cellulose, natural or synthetic polyamides, such as wool,
polyamide-6 and polyamide-6,6, polyesters, polyolefins, poly-
vinyl chloride, polyvinylidene chloride, polystyrene or
polyacrylonitrile, furthermore sheets, films, ribbons or
shaped articles made from these materials.
The water-insoluble compounds of the invention may be
used in the form of solutions in organic solvents or in aque-
ous dispersions advantageously with addition of a dispersing
agent.
Suitable dispersing agents are for example soaps, poly-
glycol ethers derived from fatty alcohols, fatty amines or
- alkylphenols, cellulose sulfite waste liquors or condensation
products of optionally alkylated naphthalene--sulfonic acids
with formaldehyde.
The compounds of the formula I may alternatively be added
to detergents, which latter ones may contain the usual fillers
29 and auxiliaries, such as alkali metal silicates, alkali metaL
-- 7 --

~ Z~ HOE 77/~ 0~1
.
phosphates or pclyme~aphosphates, alkali metal bora~es, alkali
metal salts OL carboxymethylcellulose; foam stabilizers such
as alkanolamides of higher fatty acids; or complex forming
agents such as soluble salts of ethylene-diamine-tetraacetic
acid or diethylenetriamine-pentaace~ic acid; or chemical
bleaching agents such as perborates or percarbonates.
Brightening of the fiber material with the aqueous or
possibly organic brightening liquor is carried out either ac-
cording to the exhaust process at temperatures of from prefer-
ably 20 to 150VC, or under thermosol conditions; the textile
material being adjusted to a redisual moisture content of from
about 50 to about 120 ~i by impregnation or spraying with the
brightener solution or dispersion and squeezing between rollers.
Subsequently, the textile material is subjected for about 10 to
300 seconds to a heat treatment, preferably by means of dry heat,
at temperatures of from about 120 to about 240C. This thermo-
sol process may be combined with other finishing operations,
for example application of synthetic resins in order to obtain
easy care properties.
The compounds of the invention may furthermore be added
to high molecular weight organic materials before or during
their processing. They may be added for example when manufac-
turing films, sheets, ribbons or shaped articles from the cor-
responding molding compositions, or they may be disso~ved in
2~ the spinning ma-ss before the spinning operatlon. Suitable
compounds may also be added to low molecular starting materi-
als before the polycondensation or polymerization of, for ex-
ample, polyamide-6, polyamide-~,6 or linear polyesters of the
2g polyethyleneglycol terephthalate type.
8 --
,~

~ 24~ HOE /7/E 061
,'
Compounds of the invention being substituted by one or,
preferably, two carboxy] or carbalkoxy groups may be lin~ed
to linear polyester molecules or synthetic polyamides via an
ester or an amide, when they are added to these materials or,
preferably, their starting substances under suitable conditions.
Brighteners anchored in the substrate in this manner by chemi-
cal linkage are distinguished by their extraordinary fastness
to sublimation and to solvents.
The amount of compounds of the formula (1) to be used in
accordance with this invention, relative to the material to
be optically brightened, may vary within wide limits, depend-
ing on the field of application and the intended effect, and
it may be determined easily by simple preliminary tests. Gene-
rally it is from about 0.01 to about 2 %.
` 15 The following Examples illustrate the invention, parts
and percentages being by weight unless otherwise stated.
E X A M P L E 1:
. .,
36 g (0.1 mol) of 4'-benzoxazolyl-2-stilbene-4-carboxylic
acid chloride are introduced into a suspension of 10.1 g (0.1
mol) of 2-amino-3-pyridinol in 360 ml of trichlorobenzene, and
the ~hole is stirred for 5 hours at 150 - 160C. Subsequently,
2 g of p-toluenesulfonic acid are added and the water of reac-
tion which has formed is eliminated at reflux temperature.
After having completely removed the water, the batch is cooled
to 80 C, 180 ml of methanol are added, and the mixture is re-
fluxed for a further 30 minutes. After cooling, the reaction
product is suction-filtered, and washed wlth methanol. Af~er
drying, 37.7 g (90.7 % of the theoretical yield) of the com~
2~ pound having the formula
_. n

HOE 77/F 061
~ ~- ~ -C~ - Cl~- ~ ~/ ~
are obtained which~ after recrystallization from N-methyl-
py~rolidone and clarification with animal charcoal, is pre-
sent in the form of a light yellow powder having a melting
po;nt of 330 - 333C,
Analysis: calc.found
C 77.g77.6
'A H 4~14.3
: N 10~ 9
UV-absorption: (measured in DMF)
max = 378 nm
= 8.62 x 104
E X A M P L E ?
37.4 g (0.1 mol) of 4'-(5-methyl-benzoxazolyl-2-)-stil-
~; bene-4-carboxyl;c acid chloride are introduced into a suspen-
sion of 10~1 g (0.1 moll of 2-amino--3-pyridinol in 360 ml of
;~ tetraline, and the whole is stirred for 6 hours at 150 - 160C.
Subsequently, 2 g of P2O5 are added and the water of reaction
which has formed is eliminated at reflux temperature. Split-
ting-off of water being complete, the batch is cooled to
80C~ 180 ml of methanol are added~ and the mixture is reflux-
ed for a further 30 minutes. After cooling, the reaction pro-
duct is suction-filtered and washed with methanol. After dry-
ing, 35,2 g (82 ~ of the theoretical yi~ld) of a compound hav-
;ng the formula
-- 10 --
.

~ 2~2 Ho~ 77/E 061
3 ~ ~ CH = C~
are obtained which, after recrystallization from N-methyl-
pyrroiidone with clarification by means of animal charcoal,
is present in the form of a light yellow powder having a melt-
ing point of more than 300C.
~nalysis: calc. found
C78.30 78.1
~ H4.46 4.5
:.
- N9.98 9.8
UV-absorption (measured in DMF)
max = 378 nm
~ = 8.58 x 104
''
E X A M P L E 3:
. .
- 17 g (50 mmols) of 4'-benzoxazolyl-2-stilbene-4-carboxy-
lic acid in 200 ml of toluene are converted to the acid chlo
ride with addition of excess thionyl chloride and catalytir
amounts of dimethyl formamide by refluxing for 5 hours. Sub-
sequently, excess thionyl chloride is dist~led off. After
cooling, 6.5 g (50 mmols) of 3-amino-2-chloropyridine are added,
and the batch is reîluxed for a further 16 hours. After cool-
ing, the product is suction-filtered, washed with methanol and
dried. 17.7 g (78.4 ~) of the following compound
-CH = CH- ~ -C'
- 11 -

z4~ HO_7 ~/F 051
having a melting point (crude product) of 237 - 238C are o~
tained.
E X A M P L E 4:
4.5 g (10 mmols) of the compound obtained according to
Example 3 are refluxed for 3 hours in 30 ml of dry pyridine
and 90 ml of dry dimethyl formamide with addition of 5.7 g
of dried copper acetate and 1.1 g of zinc granules. After
cooling, the batch is poured into 1 liter of water, suction-
- filtered, and the residue is precipitated by agitation irst
with 2N aqueous ammonia, subsequently with 2 % potassium car-
bonate solution, washed to neutral with water and dri~d .
4.1 g (98 % of the theoretical yield) of the following compound
CH = C~
are obtained which, after recrystallization from N-methylpyr-
rolidone, have the form of light yellow crystals having a
melting point of 340 - 342C.
Analysis: calc. found
C 78.0 77.9
H 4.1 4.0
N 10.1 10.3
~V~absorption (measured in DMF)
max = 374 nm
= 37900
E X A M P L E 5:
When 4'-(5-phenyl-benzoxazol-2)-stilbene-4-carboxylic
acid chloride is used for the batch of Example 3, and operati~ns
- 12 -

` ` lilC~29~:
. are carried out according to Examples 3 and 4, the following compound
3 ~H ~H ~
is obtained with a 52% yield relative to the carboxylic acid chloride used,
which after recrystallization from N-methylpyrrolidone with clarification by
means of animal charcoal has the form of light yellow crystals having a melt-
ing point of 300-305 C.
UV-absorption (measured in DMF)
y max = 378 nm
= 85700
EXAMPLE 6
: According to the operations of Example 1, the following compound
i-C9Hl~ ~ ~ CH = CH ~ _ ~ ~
is obtained which, after recrystallization from N-methylpyrrolidone with puri-
fication by means of animal charcoal has the form of light yellow crystals
having a melting point of 284-286C.
Analysis: calc. found
C79.85 78.9
N6.47 6.3
H7.76 7.4
'
,
- 13 -

HrJE 77/F 061
W-absorpti~n ~me.asured in DMFj
/ m x -- 378 nm
- ~ = 80100
: According to Examples 3 and 4, the following compounds are o~-
tained:
E X A M P L E 7:
~ ~ ~ CH= CH ~ X 3
. .
-.melting point 318 - 320 C
Analysis: calc. found
C 78.2 78.1
H 4.4 4.5
N 9.8 9.8
UV-absorption (measured in DMF)
I max = 377 nm
.: ~ = 86800
E X A M P L E 8:
.
~[~o>~
.~ CH3
melting point 291 - 294C
Analysis: calc. found
C 78.578.2
- H 4.84.8
N 3.5. 9.3
- 14 -
, . .

~ 24Z _ OE 7-1/E' 061
UV-absorptioll (meas~red in DMF)
max = 378 nm
~ = 85700
E X A M P L E 9:
..
i-C9H19 ~ CH=CH
UV-absorption (measured in DMF)
ma~ = 378 nm
~ = 71100